Getting Scaled Groov Data into Node-RED


I have a Modbus device which I pull data from and then scale it in Groov. Works great.


Now I want to manipulate that data in Node-RED. I thought I should be able to access that data from a Groov Read node but that node only lets me read from a Groov datastore.

How can I read my nicely scaled values into Node-RED? If I just read the raw Modbus values then I have to scale them in Node-RED. Since these are 4-20mA values I have to use some formula that I’ve never understood. The nice thing about the Groov scaling is it does that for you.



Hey Dave,

Check out the Range node - it should be a built in one.


Unfortunately at this point in time, you cant. We have plans to provide an API to each of the device types (and thus their tags), but no ETA on when.
And you are not the first to ask…


Thanks guys! In this case the Range node works perfectly for me because it mimics the scaling in Groov and allows me to get my scaled 4-20 mA data without all that hard math.

Here is a post showing how to do it manually:



Any progress here Opto22? The function of pulling Modbus values from GROOV into Node Red can be VERY useful.